Overfeed stoker



sept. 13,l 193s.

E. C. SAMMONS ovERFEEJ sToKER Filed May 6, 1935 22 ./N//EA/ TER bAMMoNPatented Sept. 13, 1938 UNITED sTATEs OVERFEED STOKER Edward C. Sammons,Portland, Oreg., assignor to Iron Fireman Manufacturing Company,

Portland, Oreg.

Application May 6, 1935, Serial No. 20,063

4 Claims.

This invention relates generally to coal burning stokers andparticularly to stok'ers of the overfeed type.

The main object of this invention is to provide a new form of overfeedStoker in which fuel is pneumatically fed from a remote storage pointinto a furnace and runiformly distributed over thev entire gratesurface.

The second object is to construct the Stoker 10 so that it may beoperated satisfactorily without regard to the kind of fuel being used,or the proportions of the various sizes and regardless of the moisturecontent of the coal and the rate of burnv ing, as well .as theparticular type of furnace i with which the stoker is used.

The third object is to tilt the discharge nozzle in a vertical plane forthe purpose of varying the trajectory of the fuel discharged therefromin order to make it possible to deliver fuel to every part of the gratesurface, lateral distribution being obtained mainly by the shape of thenozzle, while longitudinal distribution may be varied and controlled bythe elevation of the nozzle itself, or by a rocking movement thereof,sep- 25 arately or in combination with variations in the velocity of theair stream.

The fourth object is to combine a mechanical fuel feeder which willdischarge fuel at approximately the level at which it is to enter a fur-30 nace, and to convey the discharged fuel pneumatically to saidfurnace.

I accomplish these objects in the manner set forth in the followingspecification as illustrated in the accompanying drawing, in which:

35 Fig. 1 is an elevation showing my device attached to a common form offurnace showing the furnace Walls in vertical section.

Fig. 2 is a vertical section through the coal feed mechanism.

40 Fig. 3 is a horizontal section taken along the line 3-3 in' Fig. 4showing the tiltable burner nozzle in section.

Fig. 4 is a vertical section taken along the line 4-4 in Fig. 3.

45 Similar reference numerals refer to similar parts throughout theseveral views.

Referring in detail to the drawing, there is shown a common form ofgrate l0. A bridge walll extends across the rearward end of the o0 grateIll, and a furnace front I2 is indicated, with a secondary air duct I3projecting therethrough.

Air is supplied to the duct I3 by means of a fan I4 which is drivenfrom. a motor I5,v which also rotates a crank shaft |6.

. l'n the front I2 is formed a tapering recess I1 into which projectsthe nozzle |8, which is mounted on the pivot bolts I9 on the arcuateportion 20 of the nozzle holder 2|, which is secured to the front I2 bymeans of the bolts 22.. The portion 20 forms a part of a cylinder andhas 5 an opening 23 formed therein through which fuel can enter thenozzle I8. The nozzle holder 2| is provided with a flanged end 24, whichis connected to a tube 25 forming a part of the pneumatic conveyor. Itis not necessary that the nozzle I8 fit closely to the curved portion 20since air is actually drawn into the nozzle I8 through the clearancespace it is desirableto provide at this point.

On the side of the nozzle holder 2| is formed 1 5 a segment 26 providedwith a series of holes 21 along an arc struck from the axis of the pivotbolts I9.

The nozzle I8 has secured thereto an arm 28 which may be adjustablypositioned with regard to the segment 26 by means of the removable pin29, which is preferably secured on a chain 30. The arm 28 is attached atone of the holes 3| in the connecting rod 32, which is connected to acrank 33 on the crank shaft IB. It will be 25 understood that theconnecting pin 33A is made easily removable.

Air is supplied to the tube by means of a fan 34 which is operated-by amotor 35, which for the purpose of illustration, is shown as separatefrom the motor 36, which drives the fuel feeding worm 3l disposed withinthe worm casing 38, which is connected to a transfer box 39 interposedbetween the tube 25 and the fan 34. In the connecting pipe 40 betweenthe fan 34 35 and the transfer box 39 is a damper 4|, which is rocked bymeans of an arm 42 and the connecting rod 43 from the crank 44, which isd isposed on the crank shaft I6. y

It is desirable to provide the fan 34 with a form 40 of control similarto that shown in the Banfield Patent No. 1,938,241, wherein the size ofthe fan inlet is controlled by the position of an operating lever whichis referred to later as` a control lever 45. 45

It is desirable to provide the connections between the crank 44 and thedamper 4| with some means for rendering the damper 4| inoperative,preferably by means of a loose pin at either end of the rod 43.

The operation of the Stoker is as follows:

Assuming'that the damper 4| is being rocked and that the nozzle I8 isalso being rocked through the operation of the cranks 33 and 44,A whichmeans that fuel is sprayed upon the grates I0, it is evident that notonly is the trajectory of the fuel stream varied in a manner to cause itto discharge fuel along the entire length of the grates I0, but there isalso maintained a surging action in the force of the conveying air whichbrings about a complete and uniform distribution of the fuel over theentire surface of the grates IU.

It is also desirable to provide the fan 34 with some form of dampercontrol lever so that it will not only be possible to cause the air inthe tube 25 to surge, but that the quantity of air flowing therethroughcan also be varied, giving thereby an almost unlimited control in thedelivery and distribution of the fuel by the nozzle I8.

It will, of course, be understood that the motor 36 and its interveningdrive to the worm 31 in,- cludes a variable speed arrangement not shown.These are in common use in stokers of all kinds, and their purpose is tovary the rate of coal feedmg.

It is desirable to make the nozzle I8 removable and this may beaccomplished in any convenient manner, preferably by means of a flangeIBA. It is also desirable to provide openings 2 IA in the nozzle holder2| through which air may be drawn for the protection of the nozzleitself.

I claim:

l. In an overfeed stoker for continuously feeding mixed ne coal and lumpcoal to a furnace grate, a laterally widened adjustable nozzle mountedabove the grate level and pivoted so as to throw the lump coal on thegrate through different trajectories depending upon the angle to whichthe nozzle is set, a motor driven Ian, a pneumatic conveyor tubedelivering air from said fan to said nozzle, means for feeding mixedfine and lump coal laterally into the air stream in the pneumaticconveyor tube, thereby insuring the mixture of the coal with the air,means for altering at will the quantity of the air delivered by the fan,and automatic means for independently causing a regularly timed,constant increasev and decrease in the velocity of air delivered by thefan, so that the lumps will be distributed over the entire gratesurface.

2. In an overfeed stoker for a grate furnace, a pneumatic fuel conveyorduct, a motor driven fan for discharging air through said fuel conveyorduct at a high velocity, a feed worm for feeding coal into the highvelocity air stream whereby the rapidly moving air will convey the coalfrom the point of discharge of the feed worm, a nozzle at the end of thefuel conveyor duct for distributing the lump coal on the grate and fordischarging the fines into the burning space above the grate, an airduct for delivering air to a space beneath the grate of the furnace, anda second motor driven fan for discharging the main air supply forcombustion through said air duct, said motor driven fans being entirelyindependent of each other, whereby the rst fan may be of high speed,high velocity type and the second fan may be of low pressure type, andeither air supply may be changed in volume without affecting the volumedelivered by the other fan.

3. The device of claim 2 in which there is also provided means foraltering at will the quantity of the air through the pneumatic conveyorduct so that the coal will be discharged on a chosen area of the grate.

4. In an overfeed stoker for a grate furnace, a conveyor tube forfeeding air, fine coal, and lump coal to said furnace, a fan fordischarging a continuous stream of air at high velocity through saidtube, a nozzle at the end of said tube for discharging the lump coal tothe grate and the fine coal into the burning space above the grate, andautomatic means for constantly varying the velocity of the continuoushigh velocity air stream so that the fuel is constantly fed but due tothe surging of the air stream the lumps of coal are delivered to the farside of the grate when the velocity is greatest and to the near side ofthe grate when the velocity of the air stream is least, whereby theconstant change in the trajectories of the lumps of coal will tend toinsure a uniform bed of coal on the grate.

EDWARD C. SAMIMONS.

